Inscription of hard surfaces



April 7 A. M. GASPARI j 3,507,740

7 INSCRIPTION 0F HARD SURFACES A, Filed Aglil 2Q, 1968 1N VENTUR.ANTHONY M. GASPARI United States Patent 3,507,740 INSCRIPTION OF HARDSURFACES Anthony Mario Gaspari, Montreal, Quebec, Canada,as-

signor to G.M.P. Stencil Cutting Machine Company Ltd., Montreal, Quebec,Canada Filed Apr. 20, 1966, Ser. No. 543,884 Claims priority,application (glanada, Mar. 10, 1966,

954,33 Int. Cl. C09j 7/02; B24b 1/00; B32b 7/06 US. Cl. 161-167 7 ClaimsABSTRACT OF THE DISCLOSURE A stenciling mask of laminated constructionincluding a sandblast-resistant sheet in which the letters, figures andsymbols are cut and a pliable backing is secured to one planar side ofthis sheet whereby the stencil may be processed at a point remote fromthe surface to be cut in that said sheet provides a mounting for thedisconnected portions of said letters, figures and symbols.

The present invention relates to the inscription of hard surfaces andmore particularly to a method, device and apparatus for inscribing thesurface of hard objects such as stone by sand blasting.

Inscribing or lettering a hard surface such as the facing of a stonemonument or cornerstone demands skilled craftsmanship. The craftsmanfirst traces an outline of each letter or figure on the face of thestone and then carefully chisels out the letters or figures by hand.Various methods and apparatuses have been devised to facilitate thislaborious process. The most common method is to apply a material to thestone facing either as a coating which has been allowed to set or as anadhesive sheet. The material adhering to the stone facing is cut to forma stencil and the letters or figures are sand blasted onto the facingthrough the stencil. In a variation of this procedure the letters orfigures are first positioned on the facing and a blast-resistant coatingis formed around them after which the letters are either removed by handor are formed of a substance destructible by the sand blast. Thesemethods suffer from the disadvantage that the stencil must be cut on thestone since the adherence of the material of the sheet is necessary tokeep free portions, such as the unattached centers of certain letters,in their proper positions.

The present invention overcomes the above disadvantages by providing amethod, device and apparatus for inscribing hard surfaces by sandblasting in which a preformed mask may be stencilled either directly onthe facing or separate from the facing and applied thereto.

In its broadest aspect the invention consists of a method of inscribinga hard surface comprising the steps of: adhering to the surface alaminated mask of material having (1) a sheet adapted to be cut by astencilling die but resistant to erosion by sand blasting, and (2) abacking adhering to the sheet and adapted to be destroyed by sandblasting; cutting, by means of the die, portions of the sheet eitherbefore or after the adherence thereof to said surface and removing thecut portions to form a stencil of the mask; and impinging a stream ofabrasive particulate material under pressure against the stencil. Theinvention further resides in a stencilling material for use ininscribing a hard surface by sand blasting, comprising: a laminated maskhaving a sheet adapted to be cut by a stencilling die but resistant toerosion by sand blasting, and adhered to the sheet a backing adapted tobe destroyed by sand blasting, the backing being adapted to adhere tothe hard surface. The backing is preferably a material resistant tobeing cut by the die and is pressure sensitive on its exposed face foradherence to the hard 3,507,740 Patented Apr. 21, 1970 surface, theexposed face carrying a removable cover for handling. In another aspectof the invention an apparatus is provided for preparing a stencil, froma laminated mask having a sheet and a backing adhered to the sheet, forinscribing a hard surface by sand blasting, comprising: a die havingraised lettering of a depth at least equal to the thickness of the sheetof the mask; a frame to hold the die; and pressing means having a faceadapted to bear on the die and overlap the frame; the face when bearingon the die being spaced above the frame a distance equal to the depth ofthe raised lettering.

Example embodiments of the invention are illustrated in the accompanyingdrawings in which:

FIGURE 1 is a plan view of a stencil made according to the invention;

FIGURE 2 is a cross-section of the stencil taken along the line 22 ofFIGURE 1;

FIGURE 3 is a view in perspective of apparatus for cutting the stencilshown in FIGURE 1 of the drawings;

FIGURE 4 is a cross-section taken along the line 4-4 of FIGURE 3;

FIGURE 5 is a cross-section taken along the line 55 of FIGURE 3; and

FIGURE 6 is a perspective view of a lettering die used with theinvention.

Referring to FIGURES 1 and 2 of the drawings, these figures show astencil cut and ready for application to a hard surface for inscriptionby sand blasting. The stencil comprises a laminated mask 10 having sheet11 with a backing 12 adhering to one side thereof. Sheet 11 of laminatedmask 10 may be composed of any formretaining material, preferablyflexible, capable of being cut by a die but resistant to erosion by sandblasting. A suitable material for sheet 11 is one having a compositionof rubber such as that sold by Minnesota Mining and Manufacturing ofCanada Limited. Backing 12 is preferably a pressure sensitive tapematerial with an exposed adhesive surface 13 and a non-exposed surface14 adhered to sheet 11 by a glue such as a filler adhesive sold byMinnesota Mining and Manufacturing of Canada Limited. The glue isapplied to the back of sheet 11 and is removed with the portions of theletters or figures cut by the die and withdrawn to form the stencil.Backing 12 must be destructible by sand blasting and preferably alsoshould be difiicult to cut or tear. A suitable material for this purposeis a pressure sensitive tape material of pigmented polyester film soldby Du Pont of Canada Limited under the trademark Mylar which isextremely resistant to cutting or tearing but is easily eroded by theimpingement under pressure of abrasive particulate material such asaluminum oxide sand sold under the trademark Carborundum Sand by theCarborundum Company Limited (Canada). Such a backing reduces wear of thecutting edge of the die which is usually subjected to a pressure of 500to 700 pounds per square inch. Another suitable material for the purposeis a pressure sensitive tape material of pigmented polyester film soldby Minnesota Mining & Manufacturing of Canada Limited under thetrademark Silver Simlar. To enable handling and shipping a protectivecovering 15 is adhered to surface 13a of backing 12 and is adapted to bepeeled off to expose the pressure sensitive adhesive. Cover 15 ispreferably of thin plastic material.

In the method of inscribing a hard surface such as a face 20 of a stoneor monument 21 shown in FIGURE 3 of the drawings, a size of laminatedmask 10 is chosen to cover that portion of face 20 sought to beprotected against erosion by sand blasting. Cover 15 is peeled from mask10 and the mask is adhered to face 20 by means of adhesive surface 13 ofbacking 12. To cut a stencil in mask 10 individual lettering dies 22such as that shown in FIGURE 6 of the drawings (or composites of suchdies) are used. Each dies 22 comprises a mounting plate 23 and a raisedletter or figure in double outline. Raised letter 24 terminates in acuitting edge 25 which is pressed into and completely traverses thethickness of body portion 11 of sheet but leaves backing 12 intact. Die22 is then removed leaving an outline 26 of the letter imprinted throughmask 10. Strips 27 of sheet 11 bounded by outline 26 is removed in aconventional manner by a knife or other pick means leaving portions ofbacking 12 exposed corresponding to outline 26 of the letter. Facing ofstone 21 is now ready for sand blasting which, when applied against mask10, will erode and destroy the exposed portions of backing 12 leavingcorresponding portions of face 20 exposed for erosion or etching by thesand blast. It will be appreciated that backing 12 holds centralportions 28 of certain letters or figures, which retain no link with theremainder of sheet 11 of mask 10, firmly and in correct position againstthe face 20 of stone 21. When the proper amount of erosion has beenachieved by the sand blast on face 20 to inscribe the letters orfigures, mask 10 may be peeled away to expose the inscribed face.

Apparatus for carrying out the above mentioned method is shown inFIGURES 3, 4 and 5 of the drawings. This apparatus consists of a base 30having overhanging parallel flanges 31 and an upper fiat bearing surface32. A gantry 33 is mounted on base 30 by means of journalled rollers 34which move along flanges 31 in the directions of arrow 35. A crossbeam36 of gantry 33 carries a press means 37 movable along the beam in thedirections of arrow 38 which is normal to the movement of the gantryitself. As shown in FIGURE 4, press means 37 comprises a head 38 carriedon a vertical shaft 39 which is movable in a cylinder 40 axially in thedirections of arrow 41. Cylinder 40 is mounted on a C-shaped channel 42which is freely slidable on crossbeam 36 of gantry 33. A compressioncoil spring 43 carried within cylinder 40 concentrically about shaft 39bears against a shoulder 44 fixed on shaft 39 within the cylinder andurges the shaft in an upward direction. A transverse shaft 45 isjournally mounted above shaft 39 in a pair of brackets 46 fixed onchannel 42. Shaft 45 carries a circular cam 47 fixed to a handle 48which extends laterally from crossbeam 36. Thus handle 48 is movableupwardly or downwardly in the directions of arrow 49. When handle 48 ismoved downwardly the action of cam 47 against shaft 39 causes head 38 tobe lowered against the action of spring 43.

Individual stencil cutting dies 22 are held together as a group by aframe 50 consisting of a pair of elongated straight-edged slats 51 and apair of cross-arms 52 each having a slot 53. One slat 51a is fixed toeach of crossarms 52 while the other slat 51b is mounted on thecrossarms with wing nuts 54 movable in slots 53 whereby slats 51 areadjustable laterally with respect to one another.

A rectangular pressblock 55 is supplied to transfer pressure from head38 of press means 37 to dies 22. Block 55 consists of an elongated metalbar having a strip 57 of resilient padding fixed to its undersurface.

To save wear on cutting edges 23 of dies 22, block 55 is of a widthgreater than the length of mounting plate 23 of the dies. The thicknessof plate 23 of each die 22 is made equal to the thickness of slats 50and the depth of letter 24 of the die is made equal to the thickness ofsheet 11 of mask 10. Thus when head 38 applies pressure to block 55 andthe pressure is transferred to die 22, cutting edge 25 of the die willpenetrate through sheet 11 where- "upon the portions of block 55overlapping die 22 will meet slats 51 of frame 50 and prevent anypenetration of backing 12 by the die. Of course, where backing 12 iscomposed of material such as that identified above by the trademarkSilver Simlar penetration of the backing by cutting edge 25 of die 22will be prevented in any event.

An important advantage of the present invention is that the stencil maybe prepared separately from surface 20 of stone 21 to be inscribed andthen applied to the surface for the final step of sand blasting. Incarrying out this operation mask 10 is laid on a suitable platen (notshown) which restson surface 32 of base 30, with cover 15 remainingaflixed to backing 12 of the mask or with the cover temporarily removedin order to adhere the sheet to the platen. The same steps as outlinedabove are then carried out to obtain the stencil. The completed stencilis lifted from the platen and if necessary cover 15 is replaced forhandling. The stencil is then applied to surface 20 of stone 21 afterpeeling off cover 15 to expose adhesive surface 13 of backing 12. Itwill be appreciated that this method would be applicable where amonument or other work to be inscribed is not of a size and shapesuitable for placement on base 30 of the apparatus. On the other hand,the apparatus may be made portable by mounting base 30 on a suitablecarriage.

It will be seen that a distinct advance in the art of inscribing hardsurfaces has been achieved since hitherto all known methods haveinvolved laborious steps whereas the present invention is simple,requiring a minimum amount of skill while accelerating production.

I claim:

1. On a laminated stencilling mask for use in inscrib ing a hard surfaceby sandblasting of the type comprising a flexible sheet of materialresistant toerosion by sandblasting but adapted to be cut by a sharpinstrument for purposes of removing letter and symbol portionstherefrom, a pressure-sensitive adhesive on the face of said sheetwhereby said mask can be removably secured to said hard surface, theimprovement comprising a synthetic film backing adhered to and disposedbetween said face of said sheet and said pressure sensitive adhesive,said synthetic film backing being resistant to cutting or tearing butbeing easily eroded by sandblasting, whereby said stencilling mask maybe prepared separately from the surface to be treated and subsequentlyapplied thereto.

2. A stencilling mask as defined in claim 1, wherein a removableprotective covering is disposed over said adhesive prior to securementto said hard surface.

3. A stencilling mask as defined in claim 2 wherein said backing iscomposed of a material resistant to cutting.

4. A stenciling mask as defined in claim 2 wherein said backing iscomposed of a film of polyester material.

5. A stencilling mask as defined in claim 1, wherein said backing iscomposed of a material resistant to cutting.

6. A stencilling mask as defined in claim 1, wherein said sheet is of arubber composition.

7. A stencilling mask as defined in claim 1, wherein said sheet is ofrubber composition and the backing is a film of polyester material, thebacking carrying a pressure sensitive adhesive on the face thereof, anda removable protective covering of sheet plastic material adhered to thebacking by said adhesive and wherein said sheet, film and adhesive arepliable to facilitate securement to said hard surface.

References Cited UNITED STATES PATENTS 2,162,332 6/1939 Frick 161l672,270,944 l/l942 Frick l6ll 67 2,270,945 1/1942 Frick 161167 2,358,7109/1944 Helgeson 5l3ll X 3,054,703 9/1962 Brasure 16123l X ROBERT F.BURNETT, Primary Examiner R. L. MAY, Assistant Examiner US. Cl. X.R.

5l-262, 311; l6123l, 406

